Hydraulic centralizer

ABSTRACT

The centralizer comprises a pair of mutually engaging arms, movable by a hydraulic-fluid powered piston rod, for closure about a drill rod. The arms have resiliently loaded, extending pins therein which engage to inhibit an abutting closure of the arms upon each other, when powered by a first hydraulic supply. When powered by a second hydraulic supply, the pins are caused to retract into the arms, and the arms do close to an almost abutting disposition. In this latter operation, the arms grip and restrain a drill rod coupling disposed therebetween to facilitate a coupling (or uncoupling) of a drill rod therewith (or therefrom).

United States Patent Hughes [54] HYDRAULIC CENTRALIZER 24/249 WL, 249 DP24/263 D6, 263 D, 263 DA, 263 DH, 249 HA; 166/775 [56] References CitedUNITED STATES PATENTS 7 2,450,934 10/ 1948 Calhoun ..166/77.5 3,055,5139/ 1962 Kralowetz ..24/249 HA X 3,061,011 10/1962 Paget 166/775 51 Aug.15,1972

3,309,130 3/1967 Arrowood ..24/249 DPX Primary Examiner-Donald A.Grifiin Attorney-Frank S. Troidl, David W. Tibbott and Bernard J. Murphy[57] ABSTRACT The centralizer comprises a pair of mutually engagingarms,-movable by a hydraulic-fluid powered piston rod, for closure abouta drill rod. The arms have resiliently loaded, extending pins thereinwhich engage to inhibit an abutting closure of the arms upon each other,when powered by a first hydraulic supply. When powered by a secondhydraulic supply, the pins are caused to retract into the arms, and thearms do close to an almost abutting disposition. in this latteroperation, the arms grip and restrain a drill rod coupling disposedtherebetween to facilitate a coupling (or uncoupling) of a drill rodtherewith (or therefrom).

17 Claims, 5 Drawing Figures PATENTED H 1 9 3. 683. 466

SHEET 1 [IF 2 INVENTOR ROBERT W HUGHES AGENT PATENTEmuc 15 Ian SHEET 2OF 2 v at 17 INVENTOR ROBERT W HUGHES 1 HYDRAULIC CENTRALIZER Thisinvention pertains to drill rod handling means, and in particular to adevice, fluid-powdered, which centralizes drill rods, when mounted on adrilling machine feed guide structure. I

Fluid-powered drill rod centralizers are known, and usually comprisehydraulicor pneumatic-actuated arms which abuttingly close upon oneanother and cooperate to define an aperture therebetween in which tocentralize the drill rod. The known centralizers, then, have a singleoperative positioning, and lack any facility for restraining a drill rodcoupling while simultaneously providing centralizing for a drill rodcoupled to, or couplable with, the restrained coupling.

It is an object of this invention to providea centralizer for drill rodswhich will provide for remote operation.

It is another object of this invention to provide a centralizer havingmeans which grip the coupling and restrain it against rotation while thedrill rod is left unrestrained.

A feature of this invention comprises a pair of pivotally mountedcentralizing arms, movable by a fluid-powered motor, to two,operational, predetermined positions for closure upon each other tocentralize a drill rod therebetween. In one of the operationalpositions, the arms centralize a drill rod and coupling unit; in theother operational position, the arms grip and restrain a drill rodcoupling disposed therewithin while setting apart, circumferentially,from a drill rod therewithin, coupled to the restrained coupling, orfrom a rod placed therewithin for coupling thereof to the restrainedcoupling.

Further objects and features of this invention will become more apparentby reference to the following description thereof taken in conjunctionwith the accompanying figures, in which:

FIG. 1 is a side elevational view of an embodiment of the novelcentralizer, partly in section and broken away;

FIG. 2 is bottom view of the FIG. 1 embodiment, taken along the plane 22shown in FIG. 1; and

FIGS. 3, 4 and 5 are schematic representatiions of the aforenotedembodiment in three functional positions.

As shown in FIGS. 1 and 2, the novel centralizer 10, according to anembodiment thereof, comprises a pair of centralizer arms 12 which housecentralizer bushings 14 which are retained by bolts 16, and a plunger orpin 18 which is spring-loaded by disc springs 20 against a shoulder 22and retained by plate 24.

The centralizer arms 12 also support crosshead or key pins 26 whichprovide pivotal support for crossheads or keys 28. The arms 12 arepivotally mounted to a centralizer body 30 through bearings 32 and 34and cantilever pins 36. The body 30 also mounts a hydraulic cylinder 38with a piston rod 40. The end of the piston rod 40 which is moreproximate to the arms 12 defines a generally rectangular bar 42 whichhas crosshead or keyway slots 44 formed in lateral surfaces thereof. Thesizing or dimensioning of the slots 44 is such that the upper end ofpiston rod 40 is straddled by the centralizer arms 12, and the slots 44slidably receive the keys 28 therewithin.

The hydraulic cylinder 38 has a hydraulic fluid adapter 46 connectedthereto for fluid-communicating with one side of the piston (not shown)and another adapter 46a connected thereto for fluid-communicating withthe other side of the piston. Adapter 46 is connected by conduit 48 toa'closed-center, four way valve 50 serviced with approximately 200 psihydraulic pressure from a supply 8-] and by conduit 52 to open-closevalve 54 which is serviced with approximately 2,000 psi hydraulicpressure from a supply S-2. Adapter 46a is connected by conduit 56 tovalve 50. The body 30 is mounted to a drilling machine feedguidestructure 58 (only a portion of which is shown).

The novel centralizer 10 operates as follows to centralize a drill rod60 and to support the drill rod coupling 62 therein. With valve 54 inclosed position (as shown) valve 50 can be positioned to provide 200 psihydraulic pressure, from supply 8-], through conduit 48 and adapter 46to one side of the piston (not shown) of the hydraulic cylinder 38causing piston rod 40 to advance, i.e., extend. The hydraulic force istransmitted by the keyway slots 44 to the keys 28--the latter beingpivotally connected, through pins 26 to centralizer arms 12. Since arms12 are pivotally mounted to the body 30 by pins 36 the arms 12 arecaused to rotate around pins 36 in a modified scotch yoke action untilthe ends of pins 18 make contact. The 200 psi hydraulic pressure ofsupply 8-1 is not sufiicient to compress springs 20, thus a first borearea 64 formed of the centralizer bushings 14 provides the centralizingfor the drill rod 60. A second bore area 66 formed of the centralizerbushings 14 is larger than coupling 62 and, in conjunction with ashoulder 68 formed of the juncture of bores 64 and 66 defines a socketcavity for assured support of the coupling 62, and of the drill rod uponthe rod 60 being threadedly coupled to the coupling 62.

The foregoing discussion described a not unconventional functioning ofthe centralizer 10 in which the arms 12 are moved to a givenpredetermined and operational position, in which they close upon eachother, into adjacency, to centralize a' drill rod 60 therebetween, or adrill rod coupling 62, or both (i.e., a drill rod 60 with coupling 62).

This given, operational positioning is depicted in FIGS. 2 and 3. It isto be noted that the foremost extending portion of the bar 42, as FIG. 3evidences, sets in a disposition removed a distance of X from thebushing-holding tenninations of arms 12. As noted, the supply 84 is notsufficient to overcome the bias of springs 20, thus the arms 12 setapart with a space S therebetween.

In this operational positioning, the novel centralizer It] simplycentralizers the rod 60 and/or coupling 62 disposed therebetween and,with bore 64 directed downwardly and bore 66 upwardlyas though foroverhead drilling, shoulder 68 supports the coupling 62, and any rod 60coupled thereto, slidably therein against gravity. The i.d. surfaces ofbores 64 and 66 are set apart from the o.d. surfaces of the coupling 62(and any such rod 60 disposed in bore 64).

This inventive centralizer 10, however, has a second predetermined andoperational positioning in which the arms 12 grip and restrain thecoupling 62 against movement within bore 66. The selective operation ofthe centralizer for disposition in this second positioning is asfollows.

With valve 50 in closed center position (as shown), valve 54 can bepositioned to provide 2000 psi hydraulic pressure, of supply S-2,through conduit 52 and adapter 46 to the same one side of the piston ofhydraulic cylinder 38. The hydraulic force is transmitted as describedin the foregoing operation-in which the device centralized," however,the force is now sufficient to compress springs and to substantiallyeliminate the clearance space S. Now, the bore 66 grips and restrainsthe coupling 62. Bore 64 does not, however, restrain the drill rod 60;thus, the rotation drive motor of the drilling machine (not shown) cancouple or uncouple the drill rod 60 to or from the gripped andrestrained coupling 62.

In this coupling-gripping operation, the arms 12 make an almost abuttingclosure AC (FIG. 4) upon each other, because the hydraulic force issufficient both to cause pins 18 to retract into the arms 12 and toadvance the bar 42 further than that disposition which the bar 42assumed in centralizing operation. As FIG. 4 illustrates, the bar 42advances to a distance of X/2 from the bushing-holding terminations ofarms 12. Even with this near abutting closure of arms 12, the dimensionof bore 64 is sufficient to accommodate a drill rod 60 slidably therein.The near abutting closure of arms 12, however, causes the i.d. surfacesof bore 66 to engage and grip the o.d. surfaces of the coupling 62against rotary and axial movement therein.

The o.d. of a given, standard-size coupling, as represented by coupling62, is slightly greater than the id of bore 66, even with piston rod 40and bar 42 fully extended under the influence of the 2,000 psi hydraulicsupply S-2. Accordingly, during the coupling-gripping operation the arms12 stop just short of abutting closure, to assure that the maximumhydraulic force is utilized in the gripping action.

Finally, the novel centralizer 10 is selectively operative to open thearms 12 widely apart to permit a drilling machine (not shown) to traveltherethrough and therebetween. This operation is effected as follows.

With valve 54 in the closed position (as shown), valve 50 can bepositioned to provide 200 psi hydraulic pressure from supply S-l throughconduit 56, and adapter 46a, to the opposite side of the piston (notshown) of the hydraulic cylinder 38 causing piston rod 40 to retract. Bythe reverse procedure (to that described in connection with thecentralizing operation) the force applied through keys 28 againinitiates a modified scotch-yoke" motion. Arms 12 again pivot about pins36 and open to the positioning indicated in FIG. 5. This is sufficientlywide to permit the front head of the drilling machine (not shown) topass through the open centralizer arms 12.

While I have described my invention in connection with a specificembodiment thereof it is to be clearly understood that this is done onlyby way of example and not as a limitation to the scope of my inventionas set forth in the objects thereof and in the accompanying claims. Forexample, I have disclosed my invention for use with hydraulic fluid forthe enabling thereof. Actually, my novel centralizer will operate tocentralize with a pneumatic supply of energyalthough pneumatic energy isinadequate to effect the gripped restraint of the drill rod coupling.Further, bushings 14 are shown disposed to support a drill rod coupling62 on the shoulder 68 thereof for upward drilling. Yet, bushings 14,which define bores 62 and 64, and also have a coupling-access beveledsurface 70, can be turned end-for-end in arms 12, by removing thebushing mounting bolts 16, and be fixed in arms 12 in the oppositedirection. Then shoulders 68 will support a coupling 62 for downwarddrilling. These and other teachings, which those skilled in the art towhich this invention pertains will glean from my disclosure, are

comprised by the spirit of my invention.

I claim:

1. A fluid-powered drill rod centralizer, comprising:

a body;

a plurality of means mounted to said body for centralizing a drill rod,wherein at least one means of said plurality is movable, relative toother means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween;

fluid-responsive motor means;

means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; and

means supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein all meansof said plurality of centralizing means are movable, to a number of notless than two, operational, predetermined positions;

said intercoupling means couples said motor means and said allcentralizing means for effecting movement thereof by said motor means;

said supplying means comprises a plurality of sources of pressurizedfluid,

said sources of the plurality thereof defining supplies having disparatefluid pressures; and

control means operative for supplying pressured fluid from any one ofsaid sources to said motor means to effect movement of said allcentralizing means to given operational positions of said number ofpositions.

2. A centralizer, according to claim 1, wherein:

said centralizing means comprises a plurality of arms each havingrelieved surfaces, and said relieved surfaces are cooperative, uponclosure of said arms upon each other, to define an aperture therebetweenwithin which to centralize said drill rod.

3. A centralizer, according to claim 1, wherein:

said one means is cooperative with said other means, upon movementthereof to one of said positions, simultaneously to grip and restrain acoupling of a drill rod positioned therebetween, while defining acircumferential space about the drill rod and between the drill rod andsaid plurality of centralizing means to facilitate a withdrawal of saiddrill rod from such a gripped and restrained coupling thereof.

4. A fluid-powered drill rod centralizer,,comprising:

a body;

a plurality of means mounted to said body for centralizing a drill rod,wherein at least one means of said plurality is movable, relative toother means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween;

fluid-responsive motor means;

means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; and

means supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein all meansof said plurality of centralizing means are movable to a number of notless than two, operational, predetermined positions;

said intercoupling means couples said motor means and said allcentralizing means for effecting movement thereof by said motor means;

said centralizing means comprises a plurality of arms each havingrelieved surfaces, and said relieved surfaces are cooperative, uponclosure of said arms upon each other, to define an aperture therebetweenwithin which to centralize said drill rod; and

at least one of said arms has means automatically operative to inhibitan abutting closure of any surface of said one arm upon any surface ofanother of said arms.

5. A centralizer, according to claim 4, wherein:

said inhibit means comprises means projecting from a surface of said onearm for impingement thereof upon said another arm.

6. A centralizer, according to claim 5, wherein:

said projecting means comprises a pin slidably mounted within said arm;and

said inhibit means further comprises means disposed within said arm forurging said pin in projection from said arm.

7. A centralizer, according to claim 4, wherein:

said relieved surfaces are arcutely defined.

8. A centralizer, according to claim 7, wherein:

said relieved surfaces cooperatively define a plurality of substantiallyannular areas with differing crosssectional radii.

9. A centralizer, according to claim 8, wherein:

said differing radii areas cooperatively define a plurality of differingdiameter sections within said aperture, and wherein:

upon movement of said centralizing means to a given one of saidpositions, one differing diameter section of the plurality thereof gripsand restrains a coupling of a drill rod positioned therewithin whilesimultaneously, other sections of the plurality thereof set apart fromthe positioned drill rod to facilitate withdrawal of said drill rod fromthe coupling thereof gripped and restrained within said one section.

10. A centralizer, according to claim 8, wherein:

said differing radii areas are cooperative to define a plurality ofdiffering diameter sections within said aperture; and

upon movement of said arms to a given one of said positions, onediffering diameter section of the plurality thereof grips and restrainsa coupling of a drill rod disposed therewithin while simultaneouslyother sections of the plurality thereof define a space therebetween andtherewithin to facilitate an insertion of a drill rod into said spacefor the joining of such an inserted rod with a coupling thereforrestrained within said one section.

1 1 A centralizer, according to claim 4, wherein:

said relieved surfaces further cooperate to define a substantiallyannular shoulder therewithin, upon closure of said arms upon each other,to receive and arrest a coupling of a drill rod disposed therewithinagainst gravitational-induced movement from said aperture.

12. A fluid-powered drill rod centralizer, comprising:

a body;

a plurality of means mounted to said body for centralizing a drill rod,wherein at least one means of said plurality is movable, relative toother means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween;

fluid-responsive motor means;

means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; and

means supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein saidcentralizing means have at least first and second portions which, uponclosure of said one means thereof upon said other means thereof in saidpositions, become juxtaposed; and

said one means is cooperative with said other means, upon movementthereof to one of said positions, to grip and restrain a drill rodcoupling disposed between said first, juxtaposed portions of saidcentralizing means, and simultaneously, to define a space between saidsecond, juxtaposed portions of said centralizing means to facilitate aninsertion of a drill rod into said space for the joining of such aninserted rod with a coupling therefor restrained between said firstportions.

13. A fluid-powered drill rod centralizer, comprising:

a body;

a plurality of means mounted to said body for centralizing a drill rod,wherein at least one means of said plurality is movable, relative toother means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween;

fluid-responsive motor means;

means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; and

means supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein saidsupplying means comprises a plurality of sources of pressured fluid,

said sources of the plurality thereof defining supplies having disparatefluid pressures; and

control means operative for supplying pressured fluid from any one ofsaid sources to said motor means to effect movement of said one means togiven operational positions of said number of positions.

14. A fluid-powered drill rod centralizer, comprising:

a body;

a plurality of arms mounted to said body for movement thereof, relativeto said body, to a number of not less than two, operational,predetermined positions for closure thereof upon each othercooperatively to centralize a drill rod therebetween;

fluid-responsive motor means;

means intercoupling said motor means and said plurality of arms foreffecting movement thereof by said motor means; and

means supplying powering fluid to said motor means, operative fordisposing said arms for any one of said positions; wherein said motormeans comprises a fluid-actuated piston and cylinder assembly, saidassembly having an extendable piston rod projecting therefrom;

said rod has key-way-type of recesses formed in lateral surfacesthereof; and

said arms have key-type members coupled thereto in engagement with saidrecesses.

15. A centralizer, according to claim 14, wherein:

said key-type members are pivotally coupled to said arms; and said armsare pivotally coupled to said body. 16. A centralizer, according toclaim 14, wherein said supplying means comprises a plurality of sourcesof pressured fluid; said sources of the plurality thereof definingsupplies having disparate fluid pressures; and control means operativefor supplying pressured fluid from any one of said sources to said motormeans to effect movement of said arms to given operational positions ofsaid number of positions. 17. A centralizer, according to claim 16,wherein: said arms have means automatically operative to inhibit anabutting closure of any surface of said one arm upon any surface ofanother of said arms; and at least one fluid source of the pluralitythereof comprises a supply of fluid of a pressure sufficient to overcomesaid inhibit means, to cause an almost abutting closure of surfaces ofsaid arms upon one another.

1. A fluid-powered drill rod centralizer, comprising: a body; aplurality of means mounted to said body for centralizing a drilL rod,wherein at least one means of said plurality is movable, relative toother means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween; fluid-responsive motor means;means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; andmeans supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein all meansof said plurality of centralizing means are movable, to a number of notless than two, operational, predetermined positions; said intercouplingmeans couples said motor means and said all centralizing means foreffecting movement thereof by said motor means; said supplying meanscomprises a plurality of sources of pressurized fluid, said sources ofthe plurality thereof defining supplies having disparate fluidpressures; and control means operative for supplying pressured fluidfrom any one of said sources to said motor means to effect movement ofsaid all centralizing means to given operational positions of saidnumber of positions.
 2. A centralizer, according to claim 1, wherein:said centralizing means comprises a plurality of arms each havingrelieved surfaces, and said relieved surfaces are cooperative, uponclosure of said arms upon each other, to define an aperture therebetweenwithin which to centralize said drill rod.
 3. A centralizer, accordingto claim 1, wherein: said one means is cooperative with said othermeans, upon movement thereof to one of said positions, simultaneously togrip and restrain a coupling of a drill rod positioned therebetween,while defining a circumferential space about the drill rod and betweenthe drill rod and said plurality of centralizing means to facilitate awithdrawal of said drill rod from such a gripped and restrained couplingthereof.
 4. A fluid-powered drill rod centralizer, comprising: a body; aplurality of means mounted to said body for centralizing a drill rod,wherein at least one means of said plurality is movable, relative toother means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween; fluid-responsive motor means;means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; andmeans supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein all meansof said plurality of centralizing means are movable to a number of notless than two, operational, predetermined positions; said intercouplingmeans couples said motor means and said all centralizing means foreffecting movement thereof by said motor means; said centralizing meanscomprises a plurality of arms each having relieved surfaces, and saidrelieved surfaces are cooperative, upon closure of said arms upon eachother, to define an aperture therebetween within which to centralizesaid drill rod; and at least one of said arms has means automaticallyoperative to inhibit an abutting closure of any surface of said one armupon any surface of another of said arms.
 5. A centralizer, according toclaim 4, wherein: said inhibit means comprises means projecting from asurface of said one arm for impingement thereof upon said another arm.6. A centralizer, according to claim 5, wherein: said projecting meanscomprises a pin slidably mounted within said arm; and said inhibit meansfurther comprises means disposed within said arm for urging said pin inprojection from said arm.
 7. A centralizer, according to claim 4,wherein: said relieved surfaces are arcutely defined.
 8. A centralizer,according to claim 7, wherein: said reLieved surfaces cooperativelydefine a plurality of substantially annular areas with differingcross-sectional radii.
 9. A centralizer, according to claim 8, wherein:said differing radii areas cooperatively define a plurality of differingdiameter sections within said aperture, and wherein: upon movement ofsaid centralizing means to a given one of said positions, one differingdiameter section of the plurality thereof grips and restrains a couplingof a drill rod positioned therewithin while simultaneously, othersections of the plurality thereof set apart from the positioned drillrod to facilitate withdrawal of said drill rod from the coupling thereofgripped and restrained within said one section.
 10. A centralizer,according to claim 8, wherein: said differing radii areas arecooperative to define a plurality of differing diameter sections withinsaid aperture; and upon movement of said arms to a given one of saidpositions, one differing diameter section of the plurality thereof gripsand restrains a coupling of a drill rod disposed therewithin whilesimultaneously other sections of the plurality thereof define a spacetherebetween and therewithin to facilitate an insertion of a drill rodinto said space for the joining of such an inserted rod with a couplingtherefor restrained within said one section.
 11. A centralizer,according to claim 4, wherein: said relieved surfaces further cooperateto define a substantially annular shoulder therewithin, upon closure ofsaid arms upon each other, to receive and arrest a coupling of a drillrod disposed therewithin against gravitational-induced movement fromsaid aperture.
 12. A fluid-powered drill rod centralizer, comprising: abody; a plurality of means mounted to said body for centralizing a drillrod, wherein at least one means of said plurality is movable, relativeto other means of said plurality, to a number of not less than two,operational, predetermined positions for closure upon said other meansto centralize a drill rod therebetween; fluid-responsive motor means;means intercoupling said motor means and said plurality of centralizingmeans for effecting movement of said one means by said motor means; andmeans supplying powering fluid to said motor means, operative fordisposing said one means in any one of said positions; wherein saidcentralizing means have at least first and second portions which, uponclosure of said one means thereof upon said other means thereof in saidpositions, become juxtaposed; and said one means is cooperative withsaid other means, upon movement thereof to one of said positions, togrip and restrain a drill rod coupling disposed between said first,juxtaposed portions of said centralizing means, and simultaneously, todefine a space between said second, juxtaposed portions of saidcentralizing means to facilitate an insertion of a drill rod into saidspace for the joining of such an inserted rod with a coupling thereforrestrained between said first portions.
 13. A fluid-powered drill rodcentralizer, comprising: a body; a plurality of means mounted to saidbody for centralizing a drill rod, wherein at least one means of saidplurality is movable, relative to other means of said plurality, to anumber of not less than two, operational, predetermined positions forclosure upon said other means to centralize a drill rod therebetween;fluid-responsive motor means; means intercoupling said motor means andsaid plurality of centralizing means for effecting movement of said onemeans by said motor means; and means supplying powering fluid to saidmotor means, operative for disposing said one means in any one of saidpositions; wherein said supplying means comprises a plurality of sourcesof pressured fluid, said sources of the plurality thereof definingsupplies having disparate fluid pressures; and control means operativefor supplying pressured fluid from any oNe of said sources to said motormeans to effect movement of said one means to given operationalpositions of said number of positions.
 14. A fluid-powered drill rodcentralizer, comprising: a body; a plurality of arms mounted to saidbody for movement thereof, relative to said body, to a number of notless than two, operational, predetermined positions for closure thereofupon each other cooperatively to centralize a drill rod therebetween;fluid-responsive motor means; means intercoupling said motor means andsaid plurality of arms for effecting movement thereof by said motormeans; and means supplying powering fluid to said motor means, operativefor disposing said arms for any one of said positions; wherein saidmotor means comprises a fluid-actuated piston and cylinder assembly,said assembly having an extendable piston rod projecting therefrom; saidrod has key-way-type of recesses formed in lateral surfaces thereof; andsaid arms have key-type members coupled thereto in engagement with saidrecesses.
 15. A centralizer, according to claim 14, wherein: saidkey-type members are pivotally coupled to said arms; and said arms arepivotally coupled to said body.
 16. A centralizer, according to claim14, wherein said supplying means comprises a plurality of sources ofpressured fluid; said sources of the plurality thereof defining supplieshaving disparate fluid pressures; and control means operative forsupplying pressured fluid from any one of said sources to said motormeans to effect movement of said arms to given operational positions ofsaid number of positions.
 17. A centralizer, according to claim 16,wherein: said arms have means automatically operative to inhibit anabutting closure of any surface of said one arm upon any surface ofanother of said arms; and at least one fluid source of the pluralitythereof comprises a supply of fluid of a pressure sufficient to overcomesaid inhibit means, to cause an almost abutting closure of surfaces ofsaid arms upon one another.